clk: mediatek: clk-mux: Support custom parent indices for muxes

Add support for customized parent indices for MediaTek muxes: this is
necessary for the case in which we want to exclude some clocks from
a mux's parent clocks list, where the exclusions are not from the
very bottom of the list but either in the middle or the beginning.

Example:
- MUX1 (all parents)
- parent1; idx=0
- parent2; idx=1
- parent3; idx=2

- MUX1 (wanted parents)
- parent1; idx=0
- parent3; idx=2

To achieve that add a `parent_index` array pointer to struct mtk_mux,
then in .set_parent(), .get_parent() callbacks check if this array
was populated and eventually get the index from that.

Also, to avoid updating all clock drivers for all SoCs, rename the
"main" macro to __GATE_CLR_SET_UPD_FLAGS (so, `__` was added) and
add the new member to it; furthermore, GATE_CLK_SET_UPD_FLAGS has
been reintroduced as being fully compatible with the older version.

The new parent_index can be specified with the new `_INDEXED`
variants of the MUX_GATE_CLR_SET_UPD_xxxx macros.

Reviewed-by: Alexandre Mergnat <[e-mail]>
Reviewed-by: Chen-Yu Tsai <[e-mail]>
Signed-off-by: AngeloGioacchino Del Regno <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Tested-by: Fei Shao <[e-mail]>
Reviewed-by: Fei Shao <[e-mail]>
Signed-off-by: Stephen Boyd <[e-mail]>

drivers/clk/mediatek/clk-mux.c

···
 	regmap_read(mux->regmap, mux->data->mux_ofs, &val);
 	val = (val >> mux->data->mux_shift) & mask;
 
+	if (mux->data->parent_index) {
+		int i;
+
+		for (i = 0; i < mux->data->num_parents; i++)
+			if (mux->data->parent_index[i] == val)
+				return i;
+
+		/* Not found: return an impossible index to generate error */
+		return mux->data->num_parents + 1;
+	}
+
 	return val;
 }
 
···
 		spin_lock_irqsave(mux->lock, flags);
 	else
 		__acquire(mux->lock);
+
+	if (mux->data->parent_index)
+		index = mux->data->parent_index[index];
 
 	regmap_read(mux->regmap, mux->data->mux_ofs, &orig);
 	val = (orig & ~(mask << mux->data->mux_shift))

drivers/clk/mediatek/clk-mux.h

···
 	int id;
 	const char *name;
 	const char * const *parent_names;
+	const u8 *parent_index;
 	unsigned int flags;
 
 	u32 mux_ofs;
···
 	signed char num_parents;
 };
 
-#define GATE_CLR_SET_UPD_FLAGS(_id, _name, _parents, _mux_ofs,		\
-			_mux_set_ofs, _mux_clr_ofs, _shift, _width,	\
-			_gate, _upd_ofs, _upd, _flags, _ops) {		\
+#define __GATE_CLR_SET_UPD_FLAGS(_id, _name, _parents, _paridx,		\
+			 _num_parents, _mux_ofs, _mux_set_ofs,		\
+			 _mux_clr_ofs, _shift, _width, _gate, _upd_ofs,	\
+			 _upd, _flags, _ops) {				\
 		.id = _id,						\
 		.name = _name,						\
 		.mux_ofs = _mux_ofs,					\
···
 		.gate_shift = _gate,					\
 		.upd_shift = _upd,					\
 		.parent_names = _parents,				\
-		.num_parents = ARRAY_SIZE(_parents),			\
+		.parent_index = _paridx,				\
+		.num_parents = _num_parents,				\
 		.flags = _flags,					\
 		.ops = &_ops,						\
 	}
+
+#define GATE_CLR_SET_UPD_FLAGS(_id, _name, _parents, _mux_ofs,		\
+			_mux_set_ofs, _mux_clr_ofs, _shift, _width,	\
+			_gate, _upd_ofs, _upd, _flags, _ops)		\
+		__GATE_CLR_SET_UPD_FLAGS(_id, _name, _parents,		\
+			NULL, ARRAY_SIZE(_parents), _mux_ofs,		\
+			_mux_set_ofs, _mux_clr_ofs, _shift, _width,	\
+			_gate, _upd_ofs, _upd, _flags, _ops)		\
+
+#define GATE_CLR_SET_UPD_FLAGS_INDEXED(_id, _name, _parents, _paridx,	\
+			 _mux_ofs, _mux_set_ofs, _mux_clr_ofs, _shift,	\
+			 _width, _gate, _upd_ofs, _upd, _flags, _ops)	\
+		__GATE_CLR_SET_UPD_FLAGS(_id, _name, _parents,		\
+			_paridx, ARRAY_SIZE(_paridx), _mux_ofs,		\
+			_mux_set_ofs, _mux_clr_ofs, _shift, _width,	\
+			_gate, _upd_ofs, _upd, _flags, _ops)		\
 
 extern const struct clk_ops mtk_mux_clr_set_upd_ops;
 extern const struct clk_ops mtk_mux_gate_clr_set_upd_ops;
···
 			_gate, _upd_ofs, _upd, _flags,			\
 			mtk_mux_gate_clr_set_upd_ops)
 
+#define MUX_GATE_CLR_SET_UPD_FLAGS_INDEXED(_id, _name, _parents,	\
+			_paridx, _mux_ofs, _mux_set_ofs, _mux_clr_ofs,	\
+			_shift, _width, _gate, _upd_ofs, _upd, _flags)	\
+		GATE_CLR_SET_UPD_FLAGS_INDEXED(_id, _name, _parents,	\
+			_paridx, _mux_ofs, _mux_set_ofs, _mux_clr_ofs,	\
+			_shift, _width, _gate, _upd_ofs, _upd, _flags,	\
+			mtk_mux_gate_clr_set_upd_ops)
+
 #define MUX_GATE_CLR_SET_UPD(_id, _name, _parents, _mux_ofs,		\
 			_mux_set_ofs, _mux_clr_ofs, _shift, _width,	\
 			_gate, _upd_ofs, _upd)				\
···
 			_mux_ofs, _mux_set_ofs, _mux_clr_ofs, _shift,	\
 			_width, _gate, _upd_ofs, _upd,			\
 			CLK_SET_RATE_PARENT)
+
+#define MUX_GATE_CLR_SET_UPD_INDEXED(_id, _name, _parents, _paridx,	\
+			_mux_ofs, _mux_set_ofs, _mux_clr_ofs, _shift,	\
+			_width, _gate, _upd_ofs, _upd)			\
+		MUX_GATE_CLR_SET_UPD_FLAGS_INDEXED(_id, _name,		\
+			_parents, _paridx, _mux_ofs, _mux_set_ofs,	\
+			_mux_clr_ofs, _shift, _width, _gate, _upd_ofs,	\
+			_upd, CLK_SET_RATE_PARENT)
 
 #define MUX_CLR_SET_UPD(_id, _name, _parents, _mux_ofs,			\
 			_mux_set_ofs, _mux_clr_ofs, _shift, _width,	\